The present invention relates to autonomous robots generally and to autonomous robots which move through an area in particular.
Autonomous robots are known in the art and have been implemented as household appliances, such as a lawnmower or a vacuum cleaner. These household appliances operate by moving about an area to be processed such that the entire area is covered by the end of the operation.
Reference is now made to FIGS. 1A and 1B, which illustrate the operation of one exemplary autonomous robot, described in U.S patent application (Ser. No.) 08/554,691, filed Nov. 7, 1995, now U.S. Pat. No. 6,255,793, and assigned to the common assignees of the present invention. U.S. patent application (Ser. No.) 08/554,691 is incorporated herein by reference. FIG. 1A illustrates the area in which the robot 10 operates and FIG. 1B illustrates the elements, in block diagram form, of robot 10.
The autonomous robot 10 operates within an area marked with boundary markers 12A. If there are fixed obstacles 14 in the area, such as flower beds, trees, columns, walls, etc., these obstacles are rimmed with further boundary markers 12B. The boundary markers 12 can be of any suitable type, such as an electrified wire, bar coded posts, a radioactive posts, etc. The term xe2x80x9cmarkerxe2x80x9d will be used herein for both posts and wires.
As shown in FIG. 1B, the robot 10 includes a navigation system 20 which receives data from an edge sensor 22 which senses when the robot 10 approaches a boundary marker 12 where, if the marker is a continuous wire, the term xe2x80x9cmarkerxe2x80x9d indicates the section of the wire near the current location of the robot. The navigation system 20 also receives data from an odometer 24 which measures the distance the robot 10 has moved and a compass 26 which measures the current location of the robot 10.
Initially, the robot 10 is placed within the area to be covered. The robot 10 moves toward the boundary (if it did not begin near it) and then, as indicated by arrows 32, moves along the boundary, following the boundary markers 12. During this process, the robot 10 uses the location information from the compass to produce a map 28 (FIG. 1B) of the area to be covered.
Once the map is complete, the robot 10 moves about the area to be covered. Whenever it approaches a boundary marker 12, as sensed by the edge sensor 22, the robot 10 changes direction and continues until it reaches another boundary marker 12. If the boundary marker 12 appeared close to, but not at, its expected position, navigation system 20 updates the map 28 to match the new information.
If the boundary marker 12 is sensed substantially within the area, as determined by a comparison of the output of the compass 26 and the information in the map 28, the boundary marker 12 must be one which surrounds the obstacle 14. The robot 10 changes direction and continues until it reaches another boundary marker 12. The robot 10 moves about the area to be covered until it has determined that all sections of the map 28 have been covered.
However, it will be appreciated that creating the map 28 of the shape of the area to be covered is time consuming. Due to the inaccuracies of the compass 26 and odometer 24, it is also typically error prone.
Applicants have realized that, if the robot works systematically within the area to be covered, there is no need to create the map.
It is therefore an object of the present invention to provide an autonomous robot, for performing area coverage, which does not create a map of the area to be covered.
There is therefore provided, in accordance with a preferred embodiment of the present invention, a robotic system for systematically moving about an area to be covered. The system includes at least one boundary marker located along the outer edge of the area to be covered, a robot with a navigation system and a sensor unit. The navigation system navigates the robot in generally straight, parallel lines from an initial location and turns the robot when the robot encounters one of the boundary markers, thereby to systematically move about the area to be covered. The sensor unit senses proximity to one of the at least one boundary marker.
Additionally, in accordance with a preferred embodiment of the present invention, the sensor unit includes a unit for indicating proximity to an obstacle within the area to be covered and the navigation system includes a unit for turning the robot when the unit for indicating indicates proximity to an obstacle.
Moreover, in accordance with a preferred embodiment of the present invention, the unit for indicating is either a contact sensor or a proximity sensor.
Further, in accordance with a preferred embodiment of the present invention, the navigation system includes a unit for counting the number of laps need to cover the area between an obstacle and a boundary marker.
Still further, in accordance with a preferred embodiment of the present invention, the system includes at least one obstacle marker located along the outer edge of the obstacle.
Moreover, in accordance with a preferred embodiment of the present invention, the at least one boundary marker is an electrified wire receiving a first signal and the at least one obstacle marker is an electrified wire receiving a second signal.
Alternatively, in accordance with a preferred embodiment of the present invention, the at least one boundary marker is a post having a first bar code and the at least one obstacle marker is a post having a second bar code.
There is also provided, in accordance with a preferred embodiment of the present invention, a robotic system for systematically moving about an area to be covered. The system includes at least one boundary marker located along the outer edge of the area to be covered, at least one obstacle marker located along the outer edge of an obstacle within the area to be covered, a robot for moving about the area to be covered and a sensor unit for sensing proximity to the boundary and obstacle markers and for differentiating between the boundary and obstacle markers.